3D View : Abnormal(?) X-Ray mode and Edit mode interaction
when your x-ray is set to 1.0 it means that the visibility of the object is set to full. 0,5 means that the visibility is on half and 0 means that the object is completely see-through (invisible). When your shading mode is set to wireframe, wires will be visible no matter how low the visibility is set. The visibility you want is set by default. 

Visibility set to 0.5, shading - solid mode, object mode


Visibility set to 0.5, shading - solid mode, edit mode